Planner features, discussion

Hello.

I propose 2 features for planner:

1. Planner will estimate 2 x statistics: time of query with cache empty
and with cache filled.

2. Two levels of plannig: standard and long.
Long planning may be used when standard optimization
generate slow plan, and may use advanced algebraic transformations:

F( F(a,1), 2) = F(a, F(1,2) ) - for algebraic groups for example etc.

------------
pasman